Project 3: ns Simulation of Application-Level Routing

1. Project 3: ns Simulation of Application-Level Routing • Improve the application performance by user-level / application-level routing. • Understand the use of network measurement and user decisions in network route selection.

2. UDP Background Traffic at 6.1 Mbps 0 10 Mbps, 10 ms 3 10 Mbps, 10 ms 5 User sendsUDP Traffic at 6 Mbps 1 10 Mbps, 10 ms 4 10 Mbps, 10 ms 2 UDP Background Traffic at 7.3 Mbps Scenario

3. Project Description • 5 tasks: • Task0: Understand the C++ and OTcl Integration issues (0.5%) • Task1: Writing a OTcl script (2%) • Task2: Specification of measurement and selection algorithm (2%) • Task3: Write the C++ modules (6.5%) • Task4: Modify the OTcl script of task1 and test (4%) • Task5 (optional): Make algorithm adaptive to bandwidth and RTT (1%)

4. ns Setup • Follow the instructions:http://www-networking.eecs.berkeley.edu/~altmann/lectures/ee122/copy-ns_v03.htm • The process: • Download ns source code: ns.tar • Install in ~/proj3 directory in your home directory • Make changes to the Makefile (as described) or take Ye’s Makefile from the ee122 project Q&A web page • Compile ns • Make sure that you are using your ns version from now on

5. Simulation System tcl script (input) #Create a simulator object set ns [new Simulator] #Define different colors for data flows $ns color 1 Bluens Simulator Basics $ns color 2 Red #Open the nam trace filens Simulator Basics set nf [open project_b_task_1I.nam w] $ns namtrace-all $nf #open the measurement output files set f0 [open project_b_task_1I_out0.tr w] set f1 [open project_b_task_1I_out1.tr w] set f2 [open project_b_task_1I_out2.tr w] NAM (output) ns classes ns Gnuplot (output)

6. 0 10 Mbps, 10 ms 3 10 Mbps, 10 ms 5 1 10 Mbps, 10 ms 4 10 Mbps, 10 ms 2 OTcl Script – Source Routing • Source Routing • #enables source routing • $ns src_rting 1 • #set routes • set temp [$n1 set src_agent_] • $temp install_connection 2 1 5 1 3 5 • #connect transport agent with src routing agent • $udp0 target [$n1 set src_agent_] • #start simulation • $ns at 6.0 "$udp1 set fid_ 2"

7. ns Architecture • Control operations in Otcl • Class hierarchy (extract): Agent/TCP/Reno

8. ns Simulator Basics • ns is written in C++ with an OTcl interpreter as front end • ns supports a class hierarchy in C++ (called compiled hierarchy) and a similar class hierarchy within OTcl (called interpreted hierarchy). • There is a one-to-one correspondence between classes in both hierarchies. But, there are some hierarchies in C++ and OTcl that are not mirrored. • When a user instantiates a class in a OTcl script, an object of the corresponding compiled class is also instantiated through methods in the class TclObject.

9. Build New Agents / Applications: OTcl • set udp1 [new Agent/UDP/UDPar] • define new subclass of the TclClass • $ns attach-agent $n5 $udp1 • set ar1 [new Application/AppRouter] • define new subclass of the TclClass • $ar1 set packetSize_ 500 • Set default values by using bind() method • $ar1 attach-agent $udp1 • define the sequence of actions that implement the command "attach-agent" in AppRouter::command() method

10. Build New Agents / Applications: C++ • Implementation of theApplication/AppRouterclass • Name example:ar-app.cc and ar-app.h • Implementation of theAgent/UdpAgent/UdpARAgentclass • Name example:udp-ar.cc and udp-ar.h • Put them in ns-2.1b9a/mycode • Based on mm-app.cc, mm-app.h, udp-mm.ccand udp-mm.h • http://nile.wpi.edu/NS/see "Add New Application and Agent“

11. ns Files Modification • Depending on the implementation, some existing files have to be modified • Make the new protocol (of AppRouter) and its name known • common/packet.h • tcl/lib/ns-packet.tcl • Set the default value of variables • tcl/lib/ns-default.tcl • If necessary, add method definitions: • apps/app.h • common/agent.h

12. Literature and Help for ns • NS by Example • http://nile.wpi.edu/NS/ • "Add New Application and Agent“ • NS Manual • http://www.isi.edu/nsnam/ns/ • Chapter 3 of the Manual